Gas detectors which incorporate catalytic bead sensors are widely used to measure combustible gas. Such sensors can be incorporated into a Wheatstone bridge with one sensor providing a sensing function and a second acting as a reference. However, while useful, such circuit configurations are sensitive to mechanical impact. This is especially the case when bead sensors are incorporated into portable gas detectors. When a user drops a detector, the electro/mechanical structure of the Wheatstone bridge can be broken. Outputs from the bridge can be floating even without a gas reaction. This can be a problem when working in an explosive atmosphere.
FIG. 1 illustrates aspects of electrical connections and mechanical arrangements of known multiple bead sensing units.
It has been known to use a relatively simple zero compensation technique with bead sensors to make zero gas readings without knowing the reason why the zero gas reading is floating. This process has limited compensation ability and it is undesirable, with explosive gases, to permit zeroing across a wide range.